spermatogenesis 493 



parison of my specimens with those in the collection at the Acad- 

 emy of Natural Sciences, Philadelphia. There proved to be two 

 species, C. unicolor and C. vividus, m which the only marked 

 difference is the width of head and thorax. Some of my specimens 

 are slightly narrower than others, so I have probably mixed the 

 two species, and cannot state whether the 9 chromosomes belong 

 to C. unicolor or to C. vividus. 



The resting spermatogonium has a reticulum of oxychromatin 

 and linin and a plasmosome, which stains black in iron hccmatox- 

 ylin, but shows its achromatic nature in thionin (Fig. 137). There 

 were no good spermatogonial plates in the material with the smaller 

 number of chromosomes, but a lateral view of the spindle is shown 

 in Fig. 138, and the anaphase in Fig. 139. The chromatin then 

 passes into a contraction stage which is very dense, but contains 

 several clear vacuoles (Fig. 140). This has a very different 

 appearance from the contraction stage of the Membracidae. A 

 spireme stage follows where the chromatin again fills the nucleus 

 and still stains deeply (Fig. 141). The odd chromosome is first 

 visible in the rest stage (Fig. 142) where the chromatin stains 

 least and is most scattered. It is closely applied to the nuclear 

 membrane as was usually the case among the Membracidae. The 

 spireme splits longitudinally (Fig. 143), and then becomes seg- 

 mented (Fig. 144). In all stages the odd chromosome can be 

 distinguished by its small size. In the prophase of the first sper- 

 matocyte division, it can be recognized by its rounded contour; in 

 the equatorial plate, by its eccentric position (Fig. 145); in the 

 lateral view of the metaphase (Fig. 146), by its undivided condi- 

 tion; and in anaphase, by its lagging behind at one pole of the 

 spindle (Fig. 147). In the equatorial plates of the second sper- 

 matocytes with 9 chromosomes, it can still be recognized by its 

 small size (Fig. 149). As it divides in the second spermatocyte 

 division, there is no indication of it in a lateral view of the meta- 

 phase (Fig. 150), or anaphase (Fig. 151). Two of the 9 chromo- 

 somes are larger than the others {a and b in Fig. 145), and they 

 keep their individuality in the second spermatocyte {a and b in 

 Figs. 148 and 149). In all the spermatids, there is one condensed 

 body, which resembles the body called a chromatin nucleolus in 



